Conditions for branching in depositional rivers

摘要: It is often taken for granted that rivers organize transport into a single active channel. In some net-depositional environments, however, flow of water and sediment distributed in several stable channels. Such branching may be confined valleys (anabranching or anastomosed) unconfined on deltas (distributaries), their existence confronts us with the very basic question what governs spatial organization channel patterns sedimentary landscapes. Current models equilibrium morphology cannot predict occurrence because they do not consider dynamical processes such as avulsion, i.e., rapid abandonment favor new path at lower elevation. The requisite conditions avulsion have been subject ongoing debate. Here we resolve leading to show occur when dominant mechanism lateral motion. A compilation field laboratory data demonstrates frequency scales time required sedimentation beds produce deposit equal one depth. From relative rates bank erosion sedimentation, derive dimensionless mobility number accurately predicts under which anabranching distributary channels occur. Results directly applied modeling landscape evolution over human geologic scales, inverting formative environmental from deposits Earth other planetary surfaces.